This invention pertains to the art of gas turbine stator vanes, and in particular to an arrangement to obtain adequate cooling with sufficient structural integrity of the trailing edge part of a thin wall stator vane design.
With maximum operating temperatures of gas turbines increasing with advances in the art, higher cooling requirements for the turbine airfoils have been imposed. This has led to what are called thin wall designs of the stator vanes for example, with cooling being enhanced by internal pin fins which are intended to create turbulence and swirling to promote heat transfer. One of the areas in which adequate cooling is relatively important is in the trailing edge region of the vane which includes the exit slots or openings at the extreme trailing edge, and in which, with a thin wall design, the metal forming the critical throat region for the exit becomes progressively thinner. It is important to avoid any significant deformation of the metal in the trailing edge portion since it defines, with adjacent vanes, the critical throat region of the nozzle. While the internal pin fins which interconnect the two opposite walls of the vane in this region serve to a degree to strengthen the airfoil in this area, they are subject to breaking and the structural integrity of this area of the blade can be increased by adding longitudinal struts or ribs, for example as shown in U.S. Pat. No. 3,809,494. However, these struts tend to defeat to some degree the purpose of the staggered rows of pin fins in certain areas since they tend to smooth the flow as is stated in the noted patent.
The aim of this invention is to provide an arrangement of pin fins and longitudinal ribs of a character that structural integrity of the blade is insured in this area while obtaining adequate turbulence of the air to obtain the required heat transfer effectiveness.